More particularly, a process is known in which use is made of polyester foam sponges having open cells, the surface of which has been metallized beforehand, so that they are rendered conductive. The liquid containing dissolved metal is then caused to flow through these sponges which are used as the cathode. The metal becomes deposited on the walls of these sponges which are subsequently coarsely crushed and heated to a high temperature. The plastic material will then become gasified away while the recovered metal is molten and mixes with the metal which was initially coating the walls of the sponge cells.
However, it will often be found that the products in which the metal is dissolved, such as cyanide, for instance, remove the metal coating from the central part of the sponge before the metal which is to be recovered has had enough time to form a deposit. Thus, only the exterior layers of the sponges remain conductive. In this case, the yield of the recovery system is quite poor.
It is an object of this invention to provide improvements in devices of the above-mentioned type, for overcoming the above stated drawbacks.